1. Field of the Invention
The present invention relates to a scanning exposure apparatus and an exposure method, for example suitably applicable to exposure of large-area patterns on a photosensitive substrate used for fabricating liquid crystal display devices.
2. Related Background Art
Conventional exposure apparatus for exposure of large-area patterns of this kind include those of scanning types such as the step-and-repeat type for repetitively projecting small transfer images of mask through a single projection optical system onto the photosensitive substrate or the mirror projection type for projecting transfer images at magnification of unity to mask as obtained by an arc slit illumination beam through a single projection optical system onto the photosensitive substrate.
On the other hand, it is considered that a plurality of projection optical systems are arranged instead of the single projection optical system. Namely, exposure apparatus of this type are so arranged that light beams emitted from a plurality of illumination optical systems illuminate a plurality of small regions on the mask. Transfer images of these plural small regions are simultaneously projected through respective projection optical systems onto the photosensitive substrate.
As shown in FIG. 6, the transfer images P1-P5 of plural small regions are transferred as separated into a first series of transfer images including the transfer images P1, P3, and P5 and a second series of transfer images including the transfer images P2 and P4. The direction of the first series of transfer images is approximately perpendicular to the scanning direction (hereinafter referred to as the X direction) of the mask and photosensitive substrate and parallel to the Y direction within the plane of photosensitive substrate. The transfer images P1, P3, and P5 are arranged with separations 2Ly between the centers thereof. Also, the direction of the second series of transfer images is parallel to that of the first series of transfer images, and the transfer images P2 and P4 are arranged with a separation 2Ly between the centers thereof. Then, these transfer images P1-P5 are transferred by scanning in the X direction while partly overlapping in the Y direction. By this, large-area patterns are projected onto the photosensitive substrate when the mask and the photosensitive substrate are synchronously scanned.